Diurnal variation in the P300 component of human cognitive event-related potential

Diurnal variation in the P300 component of the human cognitive event-related potential (ERP) was examined. The P300 component is considered to be a measure of neuroelectric activity related to cognitive functions such as attention allocation and information processing. Nine diurnally active healthy male subjects whose sleep-wake rhythms were synchronized prior to the experiment were studied. The P300 components oral temperature, heart rate, left- and right-hand grip strength, reaction time, subjectively rated sleepiness, attention level, and fatigue were measured at 08:00, 11:00, 14:00, 17:00, and 20:00. Significant diurnal variations in P300 latency, P300 amplitude, oral temperature, heart rate, left- and right-hand grip strength, subjectively rated sleepiness, and attention level were observed. The P300 latency at 08:00 was significantly longer than at 11:00, 17:00, and 20:00, while the P300 amplitude at 08:00 was significantly greater than at 17:00 and 20:00. The P300 latency was correlated positively with subjectively rated sleepiness and negatively correlated with subjectively rated attention level. These results suggest the existence of diurnal variation in human cognitive functions.     

Identification of pain,intensity and P300 components in the pain evoked potential

This study examined the relationships among 3 components of the somatosensory evoked potential (SEP) to painful stimuli. Painful stimuli were produced using intracutaneous electrical stimulation of a fingertip and two levels of non-painful stimuli were produced by superficial electrical stimulation of a neighboring fingertip. SEPs were recorded from Cz-A1 and Pz-A1, and difference waves were computed for 3 components: (1) a pain component (the difference between SEPs to painful vs. strong but non-painful stimuli); (2) an intensity component that is not related to pain (the difference between SEPs to strong non-painful vs. mild non-painful stimuli); and (3) a P300 component (the difference between SEPs to the same stimuli under Target instructions vs. Standard instructions).The positive peaks in the 3 types of difference waves differed in both latency and topography, although with latency and topography overlap. The intensity component had an earlier positive peak than the pain component, and the pain component had an earlier positive peak than the P300 component. The pain and intensity components were larger at Cz than Pz, whereas the P300 component was larger at Pz than Cz. Under certain conditions, the pain evoked SEP consists of a weighted combination of the 3 components, complicating interpretation of the positive peaks in the recorded wave forms.     

Spatial gradient of P300 area of the brain visual evoked potential in the brain-computer interface paradigm

In 12 adult healthy subjects we studied Brain-Computer-Interface recognition of different intended letters by the square of P300 wave in the averaged VEP. Horizontal and vertical spatial gradient of this square was studied as well as tuning acuteness of visual attention to a significant letter. High acuteness of this tuning was found (width of the tuning curve at its half height was equal to 1.6 grad) independent of the letter position on the letter matrix. Horizontal and vertical gradient of P300 were found to be very similar, but in the half of cases the first one revealed some kind of the "lateral inhibition": decrease of P300 square for the columns neighboring to the meaningful one. Tuning acuteness was found to be reliable and directly interrelated with P300 square. The data are discussed in relation to selectivity of the local visual attention.     

Amplitude-time parameters of long-latency components (N1, N2 and P300) of acoustic evoked potential of healthy examinees of young and mature age

The aim of study was to track a cumulative changes of amplitude-time parametres of components N1, N2 and P300 of acoustic evoked potential in experimental situations different in complexity (at the account and listening of sounds) and to compare the received distinctions at examinees of young and mature age. ERP were recorded at 12 healthy subjects from 18 to 22 ages and 12 subjects from 32 to 59 ages. The two-stimuli oddball paradigm was used. It is revealed that components N1, N2 and P300 recorded in the situation of the listenings of sounds without any preliminary instruction do not differ at persons of young and mature age. At examinees of younger age the biger amplitude of component N1 is noted at the account of sounds in comparison with listening whereas the latency of the one do not change depending on complexity of the task. It is shown that component N2 has stability of latency in relation to age and an experimental situation. The amplitude of component N2 is above at the account of sounds in both age groups. The amplitude-time parametres of component P300 do not differ at examinees of different age in a problem of listening of sounds. The revealed features of components N1, N2 and P300 at examinees of young and mature age in experimental situations different in complexity, allow to assume that with the years at the person adaptive mechanisms which allow carrying out successfully of the task.     

P300 component changes of the auditory event-related potential in the patients with typical and atypical panic attacks

84 patients with panic disorders and 36 healthy control subjects with use of clinico-neurologic technique, psychometric, neuropsychological and the neurophysiological method of auditory event-related potentials P300 were examined. Patients with panic disorders were characterized by the raised level of anxiety, depression and cognitive function disturbances in the form of decrease of short-term memory and attention insufficiency in comparison with the healthy control subjects. Patients with atypical panic disorders differed from the patients with typical panic disorders by lower level of anxiety, a greater degree of depression and more expressed cognitive function disturbances. In comparison with the healthy control subjects with atypical panic disorders the decrease of P300 peak amplitude was observed, with typical--its augmentation. It is supposed, that P300 peak change is bound to dysfunction of temporal-limbic-reticular brain structures.     

P300 variations in parkinsonian patients before and during dopaminergic monotherapy: a suggested dopamine component in P300

P300 was recorded, using an ‘odd ball’ paradigm, in 18 parkinsonian patients before and during dopaminergic monotherapy. The data were compared with those of a homogeneous standard group of 20 subjects.The main finding was an increase in the P300 latency of parkinsonian patients before therapy, which recovered during dopaminergic monotherapy. In 11 voluntary healthy subjects the same therapy did not produce a reduction of the P300 latency.The data are discussed in relation to a possible dopaminergic component in P300 origin.     

Study of the letter and word recognition by the brain-computer-interface with P300 wave of human visual evoked potential

In four adult healthy subjects in 18 experiments, we studied Brain-Computer-Interface recognition of different intended words by P300 wave in the VEP. The set of optimal characteristics of visual stimulation which rise reliability of recognition up to 100 %, as well as effective registration locus (Pz) were determined. It was found that the best processing criteria for letter recognition were: P300 square and superposition of all three criteria (P300 amplitude, square and covariation coefficient).     

Origin of frontal N15 component of somatosensory evoked potential in man

Origin of the frontal somatosensory evoked potential (SEP) by median nerve stimulation was investigated in normal volunteers and in patients with localized cerebrovascular diseases, and the following results were obtained.

• 1.(1) In normal subjects, SEPs recorded at F3 (or F4) contralateral to the stimulating median nerve were composed of P12, N15, P18.5 and N26. Similar components were recognized in SEP recorded at Fz.
• 2.(2) In patients in whom putaminal or thalamic hemorrhages had destroyed the posterior limbs of the internal capsules, frontal N15 and parietal N18 (N20) disappeared. These components were also absent in patients with cortical (parietal) infarctions. Among these patients, the thalamus was not affected in cases with putaminal hemorrhages and cortical infarctions.

These facts indicate that the generator of the frontal N15 does not exist in the thalamus but that it originates from the neural structure central to the internal capsule, which suggests a similarity to the generator of the parietal N18.Because N15 was recorded in the midline of the frontal region with shorter latency than parietal N18, the frontal N15 might represent a response to the sensory input of the frontal lobe via the non-specific sensory system.     

The temporal component of the auditory evoked potential: A reinterpretation

The auditory evoked potentials in man cannot be explained by a single source even though a strong influence of the primary areas in the supratemporal plane has been pointed out in different works. In 26 normal adults we mathematically extracted the greater part of the experimental AEPs explicable by such an origin. The residual part obtained by subtracting this first component from the experimental data is in agreement with an origin in the precentral motor cortex.     

P100 amplitude variability of the pattern visual evoked potential

This study quantifies the amplitude variability of the pattern visual evoked potential (P-VEP) and compares this variability (1) between the two eyes and (2) between individual runs recorded in the typical clinical laboratory. Cooperative adults were studied in order to obtain measurements under optimal conditions. Average P100 amplitudes of 10 runs for one eye were essentially equal to average P100 amplitudes of the other eye, as were the variances. Mean amplitude ratio (the smaller amplitude divided by the larger amplitude) was 0.91. With a group mean P100 amplitude of 10.06 μV, standard deviation for intrasubject data was 1.84, and for intersubject data was 3.75. Therefore, most of the amplitude variability between the two eyes is due to run-to-run variability. A minimum of 3 runs (100 stimuli each) and an optimum of 5 runs should be recorded before making an evaluation.     

Differential changes of laser evoked potentials,late auditory evoked potentials and P300 under morphine in chronic pain patients

The present study investigates the differential behavior of laser evoked brain potentials (LEPs), late auditory evoked potentials (AEP) and the endogenous P300 in response to morphine treatment, examined in 6 chronic pain patients. The main result was that in parallel with marked clinical pain relief, amplitudes of the long latency LEP positivity (P400) were significantly reduced under morphine. One patient suffering from extremely painful osteoporosis for 20 years exhibited a large middle latency component (N170) which was prominently attenuated by morphine. In contrast to LEP amplitude reductions, auditory N1 and P2 potentials appeared either unchanged or even enlarged during morphine treatment. Also P300 amplitude was slightly increased under morphine. Reaction time and mood scales also failed to indicate any sedation. Obviously, LEPs reflected specifically the analgesic morphine effect in this study, while stability or enhancement of AEPs and P300 during morphine treatment indicated lack of sedation or even improved perception and concentration due to the removal of persistent pain as a disruptive perceptual-cognitive stressor.     

The use of weighted quadratic regression for the study of latencies of the P100 component of the visual evoked potential

The aim of this study was to determine the range of normal values of the latency of the P100 component of the VEP from a control population. Weighted least squares polynomial regression analysis showed that a quadratic curve best described the relationship between age and latency and separate curves, along with normal ranges, are presented for males and females. We would recommend the use of this statistical method for all determinations of the normal range of P100 latencies.     

Specific changes in auditory cognitive evoked potentials in those who participated in the liquidation of the Chernobyl accident: II. Analysis of the late P300 component

An integrated neuropsychological study and recording of auditory cognitive evoked potentials (EPs) using the three-stimulus oddball paradigm was performed in groups of ten subjects who participated in the liquidation of the consequences of the Chernobyl accident aged 50.5 ± 4.0 years and ten healthy subjects aged 47.0 ± 6.0 years. The neuropsychological study showed impairment of higher mental functions, including aspontaneity, fatigability, a decrease in the auditory-verbal and visual memories, and higher motor function deficiency, in cleanup workers (usually referred to as liquidators). Analysis of the amplitude and time characteristics of the P300 component of the auditory cognitive EP showed a decrease in the amplitude of this component in all cortical areas of liquidators in both experimental situations and for all stimuli compared to healthy subjects of the same age. Analysis of the latent period (LP) of P300 in liquidators showed the most distinct increase in the situation of passive audition for all types of stimuli. Analysis of the patterns of reactive rearrangements in different experimental situations showed that the P300 LPs of healthy subjects were similar for all types of stimuli during passive audition and were higher for the significant stimulus in the situation of counting. Liquidators were characterized by an type of response, with the LPs of responses to most stimuli increased in both experimental situations. Analysis of regional changes in the P300 LP showed that the differences in the P300 LP between the groups were the largest in the frontal areas of the left hemisphere. In addition, liquidators exhibited “uneconomical, excessive” responses as compared to normal responses, which suggests a decrease in the attention and memory capacities and could contribute to the impairment of higher mental functions. The changes in the amplitude and time characteristics of the P300 component of auditory EPs suggest deceleration of perception, processing, and analysis of information combined with weakened inhibition. The changes found in liquidators are similar to those observed in elderly people, which supports the hypotheses on accelerated brain aging and on pathological aging caused by low-dose irradiation.     

Gender differences in medium-latency acoustic evoked potentials

Medium-latency acoustic (auditory) evoked potentials (MLAEPs) were recorded in 30 men and 30 women. The MLAEPs recorded in the left and right mastoid derivations were found to be asymmetrical, the lateral differences depending on the sex: binaural stimulation and stimulation of the right ear yielded a higher total amplitude of the set of medium-latency components in the right derivation in men and in the left derivation in women. If the left ear was stimulated, there were no sex-related differences in MLAEP asymmetry. The data are discussed in terms of gender differences with respect to functional specialization of the cerebral hemispheres.     

噪声暴露对大鼠事件相关电位P300的影响及其海马水平的机制

目的：研究噪声暴露对大鼠事件相关电位（ERP）的影响及海马水平的机制。方法：雄性SD大鼠,随机均分为正常对照组（C组）、噪声暴露组（N组）。暴露条件：105dB白噪声2．5h／d×20d。观察试验过程中第0、7、14和20d ERP各波的峰潜伏期以及峰峰幅度值,并检测海马神经元尼氏体、NMDAR2B及胞内钙浓度的变化。结果：在实验第14d、第20d,噪声暴露组动物ERP P3a、P3和P3b的峰潜伏期显著增长,而且在噪声暴露20d后,大鼠海马齿状回以及CA1区尼氏体显著减少（P〈0．01）,齿状回、CA1及CA3区NMDAB2B的免疫反应强度显著降低（P〈0．01）,神经元胞内钙浓度显著升高（P〈0．01）。结论：噪声暴露可致事件相关电位的改变,这可能与其海马神经元尼氏体、NMDAR2B以及胞内钙的变化有关。     

Effect of seduksen (diazepam) on cortical P300 potentials evoked by neutral and emotional words

The influence of seduxen (diazepam) on cortical potentials P300 evoked by neutral and emotional words was studied in adult subjects having life conflicts. The therapeutic dose of seduxen (10 mg) had no significant effect on the amplitude of the late positive cortical response P300 to neutral words. Seduxen depresses the emotional activation of the cerebral cortex; that is manifested in selective elimination of those changes in latency and amplitude of P300 wave which are observed in response to emotionally significant words. Under the action of seduxen, the interhemispheric difference in the latency of cortical response disappears due to latency increase in the right hemisphere.     

Concentration effects of green odor on event-related potential (P300) and pleasantness

The effects of eight compounds, constituting the so-called "natural green odor", including leaf alcohol, on the event-related potential (P300) were investigated. In experiments with a series of single compounds, each of these eight compounds could be characterized by an overall change consisting predominantly of an increase, a decrease or no change in the amplitude of P300, whereas in experiments with a series of two-component mixtures, noticeable synergism could not be demonstrated, contrary to our expectation. Experiments with leaf alcohol (3Z-hexenol) performed at two concentrations showed a significantly different degree of pleasantness and an increase or decrease in the amplitude of P300 depending on their concentration, suggesting that concentration is important in odorant-presentation studies.     

Early positive component of the tectal evoked potential ofSqualus acanthias during electrical stimulation of the optical nerve

The evoked potential of the tectum opticum during electrical stimulation of the optic nerve was studied in acute experiments on the dogfishSqualus acanthias L. The negative phase of the "classical" negative-positive evoked potential of the contralateral hemisphere of the tectum opticum was shown to be a complex potential, including an early positive component. A similar potential also was recorded from the ipsilateral hemisphere. Enhancement of this positive potential on insertion of the recording electrode deep into the brain, its resistance to functional block on application of potassium chloride to the brain surface, and recording a similar potential from the surface of the floor of the third ventricle after extirpation of the tectum opticum are evidence of the nontectal location of the source of this evoked potential component. On the basis of existence of a focus of maximal activity in the rostral zones of the brain beneath the tectum opticum, and disappearance of the early positive component during functional block and extirpation of this brain region, it is concluded that a leading role in the generation of this component is played by thalamic nuclei.M. V. Lomonosov Moscow State University. Translated from Neirofiziologiya, Vol. 16, No. 1, pp. 61–67, January–February, 1984.